[Xr] Can the xrs argument be removed?

[Bill Spitzak]

On Thursday 22 May 2003 02:54 pm, Keith Packard wrote:

> 1)
> 	XrState		*s = XrCreate ();
>
> 	XrSetThreadState (s);
>
> 	...
>
> 	XrMoveTo (NULL, 10, 10);
> 	XrLineTo (NULL, 20, 20);
>
> 	XrStroke (NULL);
>
> 	XrDestroy (NULL);
>
> 		question -- what happens to the previous thread state?

I thought about this some, and I figured XrDestroy() would set the state back 
to whatever it is when Xr starts up initially. If you really want to remember 
the previous state you have to do XrGetThreadState first and remember it.

Perhaps XrSetThreadState() should set a pointer in the new XrState to the 
previous XrState, and XrDestroy restores this previous state. Loops have to 
be prevented somehow, perhaps setting the state moves it to the top of the 
stack. This would be convienent if a "null" state is not wanted, so that the 
Xr calls all work even if XrSetThreadState has not been called yet. Then this 
"bottom" state could point at itself and refuse to be destroyed.

> 2)
> 	XrNewState ();
>
> 	XrMoveTo (10, 10);
> 	XrLineTo (20, 20);
>
> 	XrStroke ();
>
> 	XrDisposeState ();
>
>
> 		question -- how to manage multiple states?

I don't think this is wanted, as you already have XrSave/Restore which would 
do everything this can do, right? If in fact this is the best way to 
implement XrSave/Restore then they can be written to do this internally.

-- 
                   ,~,~,~,~ ~ ~ ~ ~
     /\_       _|_========___         Bill Spitzak
 ~~~/\/\\~~~~~~\____________/~~~~~~~~ spitzak at d2.com